1. Field
The present disclosure relates to methods and devices for sensing. In particular, it relates to devices and methods for nanowire electron scattering spectroscopy.
2. Related Art
Optical fluorescence techniques are capable of single molecule sensitivity and are well suited to surveying relatively large volumes. However, optical techniques require labeling with fluorescent “tags”, an optical excitation source, and optical detection.
Carbon nanotube (CNT) based chemical sensors offer significant advantages over traditional metal-oxide-based electrical sensors such as chem.-FETs, including very high sensitivity approaching single molecule detection. However, the optimization of such sensors is still in its infancy. It was only very recently that room temperature operation of very sensitive (about 2 ppm) CNT-based chemical sensors was first demonstrated. See Kong J, Franklin N, Zhou C, Chapline M, Peng S, Cho K, Dai H, Nanotube Molecular Wires as Chemical Sensors, Science, 287, 622. Such sensors respond to many charged or charge-donating molecules in a similar fashion, and rely on chemical functionalization of the CNT to provide chemical specificity. In particular, chemically functionalized nanowires with preattached chemical receptors tailored to individual molecules of interest must be used.
Therefore, this additional, costly functionalization step must be done differently for each type of molecule and many differently functionalized nanotubes would be required for detection of a broad range of chemicals. As a consequence, while potentially effective, this functionalization requires labor-intensive treatment of many nanowires to sense a broad spectrum of molecules.